Change the default schedule type
Change the default schedule type

The thread_pool schedule is not complete whereas the thread_per_process
schedule is at least implemented.

Kitware/sprokit,linus-sherrill/sprokit,linus-sherrill/sprokit,mathstuf/sprokit,Kitware/sprokit,mathstuf/sprokit,linus-sherrill/sprokit,Kitware/sprokit,mathstuf/sprokit,mathstuf/sprokit,linus-sherrill/sprokit,Kitware/sprokit